Gulf of Mexico Oculina varicosa Project

The Gulf of Mexico Oculina varicosa Project aims to genetically identify a deep-water coral species in the Gulf of Mexico believed to be Oculina varicosa, and then characterize the species’ abundance, distribution, and habitat within the Eastern Gulf of Mexico.(1) Oculina varicosa is currently considered a “Species of Concern” (SOC) for potential listing under the Endangered Species Act (ESA) and was believed to only exist in any abundance at one location off the eastern coast of Florida.(2, 3)

This project is a collaborative effort with the Association of Underwater Explorers (AUE). AUE’s director, Michael Barnette, is a fisheries biologist with NOAA’s National Marine Fisheries Service who originally documented the deep-water Gulf of Mexico Oculina population (4), and, in the past, has collected Oculina varicosa from Oculina Bank off the east coast of Florida for Harbor Branch Oceanographic Institution and Florida State University. Michael Barnette is a highly-experienced technical diver who has participated on projects to depths in excess of 120 meters. Therefore, he and his team are uniquely experienced to conduct the coral collections and species’ characterization.

Summary

Phase One of the project entailed the collection of samples of a deep-water coral species believed to be Oculina varicosa for genetic analysis. The results of the analysis identified the coral as a genetic match to the Oculina varicosa populations in the Atlantic.(5) This positive identification is significant for the understanding of the species and, ultimately, for its management and protection.

Phase Two of the project will involve dives to characterize the species’ abundance, distribution and habitat within the Eastern Gulf of Mexico. It is important to know where and how much coral exists throughout the Gulf of Mexico before decisions about the health and protection of the species can be made. This information will be utilized to designate additional management measures to protect the species (e.g., protected areas) and aid in species recovery. This work will likely have significant implications for Oculina on the east coast of Florida, as the Gulf of Mexico may be the sources of larval recruitment for Atlantic populations.

Background and Objectives

The coral genus Oculina has a confused taxonomic history. While several species occurring off Florida through North Carolina have been named, their validity has been questioned. Sequence data from three nuclear genes suggests that these named species are not genetically isolated (5). However, a deep-water (i.e., >70 meters) population of Oculina varicosa found off the central east coast of Florida (i.e., Oculina Bank) appears to be genetically isolated from all other Oculina varicosa off the United States.(3) This finding has potential conservation and management importance, as the species is currently classified by NOAA’s National Marine Fisheries Service as a SOC for potential listing under the ESA. The species’ current status was designated based on extant trend information (i.e., severe decline) from the Experimental Oculina Research Reserve at Oculina Bank. At present, this is the only population of Oculina that has been described from deep water. In 2005, however, Michael Barnette and AUE divers located abundant Oculina habitat from depths of 66-75 meters off the West Florida Shelf in the Gulf of Mexico.(4)

In its Red List assessment of Oculina varicosa, the International Union for the Conservation of Nature (IUCN) outlined recommended measures for conserving the species: “research in taxonomy, population, abundance and trends, ecology and habitat status, threats and resilience to threats, restoration action; identification, establishment and management of new protected areas; expansion of protected areas; recovery management; and disease, pathogen and parasite management.”(6) Furthermore, the SOC description for Oculina varicosa details the species’ data needs thusly: “Better data is needed on the levels of recruitment for both deep and shallow populations as are any sort of population data from different geographic areas (besides Central Florida).” The expected results of the proposed project would directly address most of these conservations recommendations and data needs. The work that would be funded by this grant would yield essential information on the taxonomy and population significance of Oculina varicosa in the Gulf of Mexico. Specifically, it would provide a clear determination of whether deep-water Oculina varicosa from the Gulf of Mexico is distinct from other species and populations of Oculina, and the potential relationship and importance of Gulf of Mexico Oculina may have with Atlantic populations.

Phase I – Species Identification (COMPLETED 2009)

A team of divers and support personnel from the Rubicon Foundation and the Association of Underwater Explorers traveled to the newly-identified Oculina habitat area in the Gulf of Mexico, which is approximately 150 nautical miles west of Tampa Bay and 50 nautical miles south of Cape San Blas, Florida. Divers utilized closed-circuit rebreathers, standardized bailout gasses, and proprietary decompression profiles. At each sample site, in situ photographs of representative habitat were taken. Living Oculina coral specimens (i.e., 2-3 centimeters each, containing 5-8 coral polyps) were hand-collected by divers. Approximately 40 samples in total were collected from four distinct areas as distant from each other as possible. Colonies from each sampling area were spaced at least 5 meters apart to avoid re-sampling clonemates. From each of the four sampling areas, specimens were placed in 95 percent ethanol (non-denatured). Specimen preservation was conducted on the boat after completion of diving activities. Samples were sent to Louisiana State University for genetic analysis.

Although sequence markers are best suited for drawing inferences about population history, mtDNA in anthozoans has proven too slowly evolving for use within species. As an alternative, Dr. Hellberg, Associate Professor in the Department of Biological Sciences, Louisiana State University, has developed three nuclear sequence markers from expressed sequence tags drawn from a cDNA library. Dr. Hellberg has already compiled population samples and DNA extractions from nine shallow-water Oculina populations spanning their range between North Carolina and Panama City, Florida.(3)

Analysis concluded that the Gulf specimens were genetically identical to the deep-water population found on the Atlantic coast of Florida.(5)

We propose to survey three distinct areas (i.e., north, central, south) along the 40-fathom break off the West Florida Shelf where deep-water Oculina may occur. The north site is a confirmed area where Oculina was previously documented and sampled by the principal investigator, which is approximately 40 nautical miles south of Cape San Blas. The central site is an area specifically known as the “Elbow,” which is approximately 80 nautical miles west of Tampa Bay. The southern site is approximately 95 nautical miles west of Naples. The expected results of the proposed project would directly address most of the IUCN conservation recommendations, as well as address explicit SOC data deficiencies, and provide essential information for species’ conservation and management.At each of the three survey sites, a team of two divers will descend to the bottom and initiate a 1-kilometer survey transect parallel to the high-relief ledge habitat using diver propulsion vehicles (DPVs). High-definition video cameras attached to the DPVs and angled 90 degrees towards the ledge habitat will document any Oculina variocosa coral present. A second team of divers will conduct a second 1-kilometer transect in the same general area, extending total survey coverage to 2 kilometers at each site. Towed marker floats will allow the vessel to accurately map each survey transect.

Living Oculina varicosa coral specimens (i.e., 2-3 centimeters each, containing 5-8 coral polyps) will be hand-collected by divers at the beginning and end of each transect for genetic analysis. Specimen preservation will be conducted on the boat after completion of diving activities. Samples will then be sent to Louisiana State University for genetic analysis.

Video footage will be encoded for subsequent Oculina abundance and distribution assessment and habitat evaluation. Upon completion of the project, all video will be contributed to the NOAA Video Library. Results of the project will be documented promptly in a NOAA Technical Memorandum. Additional studies detailing abundance and distribution, as well as population dynamics based on genetic analysis, of Oculina in the Eastern Gulf of Mexico will be submitted to relevant journals for peer review and publication.